Satellites are being in increasingly diverse range of important applications. Today, satellites provide a host of communication, weather, military and scientific services. The increasing use of satellites makes their operational accuracy of increased concern.
For example, many satellites provide a mission sensor that provides important data about some physical quantity. For example, weather satellites may provide radar system that tracks changes in weather. A communication satellite may provide an antenna that receives and transmits remote communication transmissions. An intelligence satellite may provide images of a selected location on the earth's surface. In each of these cases, the mission sensor provides an important service for the operation of the satellite.
One important issue in the calibration of these satellites is the determination of mission sensor alignment. Typically, past methods of determining the alignment of the mission sensor have relied upon a complicated procedure on the ground. This ground alignment typically involves setting up the mission sensor and representing its operational axis with some type of optical reference surface. The sensors may not even be activated during this procedure. Unfortunately, this type of alignment procedure is time consuming and expensive. Additionally, this on-the-ground alignment suffers from inherent limitations. For example, the optical reference may not precisely represent the sensor active axis. As another example, the effects of Earth's gravity on the satellite may distort the alignment when compared to its eventual operational environment. Additionally, aligning the mission sensor to optical reference surfaces suffers from inherent inaccuracies.
Thus, what is needed is an improved system and method for determining the alignment of satellite sensors that provides for increased accuracy and reduced costs.